1. Field of the Invention
The present invention relates generally to door closers or operators that utilize a compression spring to apply force to close a door. More specifically, the present invention relates to a spring adjuster and indicator for use with a door closer or operator, which allows for adjustment of the spring closing force while the door closer housing remains stationary, while also providing a visual indicator of the level of spring compression.
2. Description of Related Art
Some conventional window or door closers or operators utilize a compression spring to apply force to close the door or window. As utilized herein, the term “door” also includes a window that is similarly operated, e.g., by pivoting movement on a pivot or hinge. An embodiment of a typical prior art door closer 120 is shown in FIG. 1 and includes a closer housing 122 that in part defines a substantially cylindrical reservoir, a piston 126 and compression spring 130 biased against the piston 126. A rack 138 is attached to the piston 126. The rack 138 is driven by a pinion 140 through engagement with the teeth 142 of the pinion 140. The pinion 140 is connected to a closer arm assembly (not shown) for operably coupling the door closer 120 to a door. FIG. 1 shows the door closer 120 in a position corresponding to a closed door. As the door is opened, the pinion 140 rotates in an initial direction, transporting the rack 138 and consequently sliding the piston 126 to the right as shown in FIG. 1. The compression spring 130 urges the piston 126 and rack 138 to the left in FIG. 1. When the force of the compression spring 130 overcomes the input force from the door and pinion 140 such as when the door is released, the compression spring 130 will force the piston 126 to the left in FIG. 1, and the pinion 140 will rotate in a direction opposite the initial direction and the door closer 120 will act to close the door.
The spring in a door closer or operator indirectly applies force to the door in the closing direction. The amount of spring force or tension is determined by the geometry of the spring and the amount of preload applied by compressing the spring from its static length. Presently, adjusting the spring setting in closers is often done with an adjusting screw using a tool to turn the adjusting screw. U.S. Pat. No. 8,732,905 discloses an example of a door or window closer using an adjusting screw that has an external end that is turned by a nut, knob or socket.
Determining the spring force setting of a closer or operator on a door is typically done by counting the number of turns on a spring adjust screw on the closer. However, there is no indication of the current spring preload prior to adjustment or after past adjustments, unless documented. It must then be checked by measuring the force on the door. A need exists for a means for an installer to be able to visually determine where the spring force is set while installing the closer.